1. Technical Field
The present invention relates to a liquid pressure meter, a liquid level meter, and a warning system.
2. Related Art
As a device that senses water levels (liquid levels), for example, a liquid level meter of JP-A-2009-287927 is known. The liquid level meter of JP-A-2009-287927 includes: a post main body having an internal space and an entry port through which a liquid is entered into the internal space; a proximity detection device provided inside the internal space; and a floating member that floats on a liquid surface of the liquid entered into the internal space. The floating member has an IC tag. The proximity detection device has plural IC tag readers arrayed in the direction of height. The liquid level meter of JP-A-2009-287927 is configured in such a way that the number (combination) of IC tags that can be read by the IC tag readers changes according to the height of the liquid surface of the liquid entered into the internal space and the liquid level is detected by following the change.
However, in the liquid level meter of JP-A-2009-287927, since no hole is formed for releasing air that exists in the internal space, the air remains in the internal space and this residual air obstructs the entry of a liquid from the entry port. Therefore, the liquid level meter of JP-A-2009-287927 has a problem that liquid levels cannot be detected accurately.